Marine Interpretation Message
Issued by NWS

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000
AGNT40 KWNM 301258
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
858 AM EDT SUN AUG 30 2015

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

AS PREVLY EXPECTED...THE QUIET PATTERN CONTS ACRS THE CSTL/OFSHR
WTRS. A LOW PRES CENTER NR 35N73W CONTS TO TRACK NE ALONG A STNRY
FRONT WITH MAX ASCD WINDS GNRLY IN THE 15-20 KT IN ITS IMMED
VCNTY. ELSEWHR WEAK GRADIENTS PERSIST WITH MAX WINDS 10-15 KT...OR
LESS...THRUT THE RMNG WTRS. MAX SEAS THRUT THE WTRS ARE IN THE 4-6
FT RANGE...HIGHEST ACRS THE IMMED SE QUADRANT OF THE LOW PRES
CENTER...WHICH ARE BEING HANDLED FINE BY THE 06Z WAVEWATCH III AND
00Z ECMWF WAM MDLS AT THE MOMENT.

OVER THE SHORT TERM...THE LATEST MDLS ALL FCST THE LOW PRES CENTER
TO PASS E OF THE CNTRL NT2 WTRS TODAY. THE MDLS THEN SHARE SMLR
FCST TIMING FOR A WEAK COLD FRONT TO MOV TO THE NEW ENGLD COAST
LATE MON...THEN PUSH SSE ACRS THE NT1 WTRS MON NITE WITH MAX ASCD
WINDS GNRLY IN THE 15-20 KT RANGE. WITH THE 06Z NAM/GFS BEING
CONSISTENT VS THEIR PREV RESPECTIVE RUNS...WL CONT TO USE THE
PREVLY POPULATED 00Z GFS 10M BL WINDS THRU MON NITE WITH JUST SM
MINOR TWEAKS MAINLY IN DEFERENCE TO THE 00Z ECMWF. SO PLAN ON
MAKING NO MAJOR SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...THE LATEST MDLS GNRLY AGREE THAT THE COLD
FRONT WL PUSH S ACRS THE NRN NT2 WTRS TUE/TUE NITE...THEN BCM
STNRY ACRS CNTRL NT2 WTRS WED/WED NITE WHL WKNG WITH ASCD
WINDS DMNSHG TO LITE AND VRBL. A BLENDED 06Z/00Z GFS AND 00Z ECMWF
SOLUTION THEN FOR THE REMAINDER OF THE EXTENDED FCST PERIOD LOOKS
RSNBL WITH WEAK GRADIENTS WITH LITE WINDS CONTG. SO ANTICIPATE
MAKING ONLY MINOR LONG RANGE TWEAKS IN THE NEXT OFSHR FCST
PACKAGE.


-----------------------------------------------------------------
PREVIOUS DISCUSSION...

SHORT TERM...A HI-RES ASCAT PASS FROM 0100-0240Z CLEARLY
INDICATED A WEAK LOW PRES AREA NR 35N 74W...OR ROUGHLY 70-80 NM
E AND SE OF CAPE HAT. THE PASS ALSO INDICATED WEAK HIGH PRES
CENTERED JUST E OF THE NE NT2 OFF WTRS OR NR 39N 63W. THE
STRONGEST WINDS WERE NOTED JUST TO THE E AND SE OF THE LOW...
WITH WIND SPEEDS UP TO 20 TO 25 KT. THE LATEST RADAR...SATELLITE
AND LIGHTNING DENSITY IMGRY SHOWS SCTD SHWRS AND TSTMS OVR MOST
OF SRN AND CENTRAL NT2 OFF WTRS...OR MAINLY S OF 37N. THIS
ACTIVITY WILL PERSIST FOR THE NEXT FEW DAYS AS THE WK LOW PRES
AREA MOVES NE AWAY FROM THE WTRS LEAVING BEHIND A WEAKENING
STATIONARY FRONT. LOCALLY GUSTY WINDS AND ROUGH SEAS CAN BE
EXPECTED IN OR NR ANY HEAVY TSTMS OVR THESE WTRS DURING THE NEXT
DAY OR TWO. OVERALL...THE 00Z MDLS REMAIN VRY CONSISTENT AND IN
DECENT AGREEMENT OVR THE REGION THRU EARLY PARTS OF THE WK. WE
WILL REMAIN CLOSE TO THE 10M GFS WINDS FOR THE EARLY AM PACKAGE
FOR TODAY THRU TUE NITE AS A RESULT...BUMPING UP WINDS SOMEWHAT...
UP TO 5 KT HIGHER THAN THE 10M GFS WINDS...TO THE E AND SE OF THE
LOW AS NOTED BY THE EARLIER ASCAT PASS FOR TODAY. A WEAK COLD
FRONT IS STILL FCST TO APPROACH THE NEW ENGLAND COAST LATER
MON...THEN CROSS NT1 WTRS MON NITE...THE NRN NT2 WTRS TUE...AND
THEN STALL OVR THE CENTRAL NT2 WTRS TUE NITE. OVERALL...NO MAJOR
CHANGES WILL BE MADE TO THE PREV FCST FOR THE AM PACKAGE FOR
TODAY THRU TUE NITE.

LONG TERM...THE 00Z MDLS REMAIN IN PRETTY DECENT AGREEMENT WED AND
WED NITE...ESPECIALLY THE 00Z GFS AND 00Z ECMWF MDLS. THE 00Z
UKMET MDLS WANTS TO BRING THE REMNANTS OF T.S. ERIKA E TOWARD THE
FAR SE U.S. COAST BY THU. WHILE NOT IMPOSSIBLE...THIS SCENERIO
SEEMS RATHER UNLIKELY AT THIS TIME. WE WILL REMAIN CLOSER TO THE
00Z GFS FOR WED INTO WED NITE...AND THEN TRANSITION TO A 50-50
BLEND OF THE 00Z GFS AND 00Z ECMWF FOR THU AND THU NITE...AS SOME
SUBTLE DIFFERENCES BECOME MORE EVIDENT AT THAT TIME FRAME...WITH
A MDL BLEND LKLY DIMINISHING FCST ERROR. MDL DIFFERENCES INCREASE
BEYOND THU NITE...WITH THESE DIFFERENCES BEING ADDRESSED LATER
TODAY AS THE FCST IS EXTENDED BEYOND THU NITE AT THAT TIME.
OVERALL...NO MAJOR CHANGES TO THE PAST FEW OPC FCSTS CAN BE
EXPECTED FOR THE LONG TERM PORTION OF THE OFF FCST...WITH HIGH
PRES BUILDING OVR THE WTRS WED AS A STNRY FRONT DISSIPATES OVR
CENTRAL NT2 WTRS. THE HIGH WILL MOVE OFF TO THE E OF THE WTRS THU
AS THE NEXT COLD FRONT MOVES S INTO NT1 AND PSBLY NRN NT2 OFF
WTRS. WEAK LOW PRES MAY TRY TO FORM ALONG THE FRONT OVR NRN NT2
WTRS THU NITE...PER THE 00Z ECMWF MDL.

SEAS...SEAS HEIGHTS ARE RUNNING GENERALLY WITHIN A FT OR SO OF THE
00Z WNA WAVE WATCH III MLD GUID EARLY THIS MORNING. AS WE WILL BE
FOLLOWING THE 00Z GFS FOR WINDS FOR TODAY THRU WED NITE WE WILL
ALSO REMAIN CLOSE TO THE 00Z WNA WW3 MDL OUTPUT FOR THE SAME TIME
FRAME. AS WE TRANSITION TO A 50-50 BLEND OF THE GFS-ECMWF FOR
WINDS THU AND THU NITE WE WILL ALSO USE A 50-50 BLEND OF THE 00Z
WNA WW3 AND 00Z ECMWF WAM FOR THE SEA HTS FCST FOR THAT TIME
PERIOD.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.


.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
     NONE.

$$

.FORECASTER VUKITS/MILLS. OCEAN PREDICTION CENTER.



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